Il VLTI osserva di nuovo la più grande stella iper gigante gialla mai scoperta
A prima vista non sembra granché, ma questa macchia mostra una stella notevole chiamata V766 Centauri (abbreviato V766 Cen) e la sua compagna. Essa è stata studiata per la prima volta e classificata alcuni anni fa da ricercatori che hanno usato lo strumento Very Large Telescope Interferometer (VLTI) di ESO. All’epoca è stato scoperto ch’era una stella chiamata “iper gigante gialla”, una stella massiccia e luminosa estremamente rara - e estremamente grande !
Il diametro è 1400 volte quello del Sole, V766 Cen non solo è la più grande stella di questo tipo mai scoperta, ma è anche una delle dieci stelle più grandi mai scoperte.
Tuttavia uno studio recente ha suggerito che V766 Cen sia probabilmente in una fase della sua vita appena prima di quella di una iper gigante gialla: una super gigante rossa evoluta, che perde la sua massa così velocemente che tornerà alla fase di super gigante gialla più calda per un corto lasso di tempo. In ogni caso la stella è un vero colosso ed è molto interessante per gli scienziati che cercano di capire di più a proposito di questo stadio inusuale nel ciclo di vita delle stelle.
Un team di scienziati ha ora usato il VLTI di nuovo per studiare V766 Cen con maggiori dettagli. Usando la rete dei quattro telescopi ausiliari e uno strumento montato sul VLTI chiamato PIONIER (the Precision Integrated-Optics Near-infrared Imaging ExpeRiment), il team ha fotografato V766 Cen e la sua compagna con impressionanti dettagli. Hanno trovato che la compagna è più piccola e più fredda della sua partner - probabilmente una gigante fredda o super gigante con un raggio di circa 650 volte il raggio del Sole. Avere una compagna vicino è assai tipico per una stella massiccia ed è importante nel processo di evoluzione stellare.
Questa foto della settimana mostra V766 Cen in tre epoche diverse. Queste immagini contengono entrambi V766 Cen e la sua compagna - nella prima immagine, la compagna passa dietro V766 Cen, ma nella seconda e nella terza immagine la compagna passa davanti ed è visibile come una macchia brillante.
Link
ESO/M. Wittkowski (ESO)
Riguardo l'immagine
| Identificazione: | potw1740a |
| Lingua: | it-ch |
| Tipo: | Collage |
| Data di rilascio: | Lunedì 02 Ottobre 2017 06:00 |
| Grandezza: | 984 x 416 px |
Riguardo all'oggetto
| Nome: | HR 5171 |
| Tipo: | Milky Way : Star : Evolutionary Stage : Red Supergiant Milky Way : Star : Grouping : Binary |
| Distanza: | 12000 Anni luce |
Formati delle immagini
Colori e filtri
| Banda | Lunghezza d'onda | Telescopio |
|---|---|---|
| Infrarosso | 1.59 μm | Very Large Telescope Interferometer PIONIER |
| Infrarosso | 1.58 μm | Very Large Telescope Interferometer PIONIER |
| Infrarosso | 1.58 μm | Very Large Telescope Interferometer PIONIER |
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